It's a Bowtech Admiral (30" ATA iirc). The bow is very quiet for the most part but I can definitely hear a little string buzz without any silencer on it.
With that short of bow and the suppressor it makes the use of traditional silencers like Cat Whiskers and Bateman Puffs difficult. In that case I would agree with MLB if you don't want either of the Sims products. Monkey Tails, while not as efficient over all frequencies as the original NavCom Leach, do seem to be more durable and nearly as effective.
How old were the Leaches you had on the bow? Shelf life of NavCom is rather short when exposed to the environment. So, like peep tubing, they should be replaced every year. Or more if you shoot frequently.
When I shot the Admiral I thought is was definitely quiet. But I did get a lot of E-Clip vibration. If you are experiencing something similar, string wax or silicone RTV placed on the E-Clips is very effective.